WATER BEYOND EARTH: A REMOTE-SENSING PERSPECTIVE on THE ROLE OF AQUEOUS PROCESSES IN OUR SOLAR SYSTEM

Water has without question played an important role in the evolution of our solar system. In particular, both laboratory and remote spectroscopic techniques have led to the discovery of hydration on Mars, meteorites and potential asteroid parent bodies, the dwarf planet Ceres, and more recently the surface of the Moon. From the days of early telescopic observations to the modern era of orbital hyperspectral reflectance data, Mars has been shown to be a dynamic planet in the past and present with respect to aqueous processes. Most recently, visible-near infrared reflectance data from the OMEGA and CRISM spectrometers have detected a variety of hydrous minerals indicative of equally diverse aqueous environments in the early history of Mars. Coupled with laboratory and theoretical studies, these remotely-acquired data have also led to the first quantitative spatial and temporal maps of the water content of the optical surface. Beyond Mars, recent interpretations of ground-based telescopic data of Ceres, a target of NASA’s DAWN mission, have suggested the presence of significant amounts of brucite and Mg-carbonates on the dwarf planet. This composition puts into question proposed compositional and genetic links between this body and the carbonaceous chondrites, and it may even suggest Ceres has experienced more extensive aqueous alteration than anything represented in current meteorite collections. Possible origins of this mineral assemblage include a two-stage low-temperature alteration process in which brucite was formed from olivine and then interacted with CO₂-bearing fluids to form Mg-carbonates, or one in which carbonates were altered at high-temperatures in the interior to form periclase, which then interacted with fluids to form brucite. More recently, and closer to home, orbital data have led to the discovery of dynamic hydration of the lunar surface. Though initial characterization has begun, there are several potential sources of this water and future missions will be required to fully quantify these volatiles on spatial and temporal scales. In addition to these exciting discoveries, this talk will examine the past, present, and future of remote spectroscopic techniques for addressing outstanding questions related to the amount and extent of aqueous alteration in our solar system.